Systems that include actuators, sensors, motors, or other electronic/mechanical devices often use control signals that need to be adjusted to ensure proper operation. A common way to design such a system is to configure the system in a feedback loop structure. Such a system is typically referred to as a feedback control system.
The basic feedback structure includes the main system process that is being controlled (sometimes referred to as the “plant”), a controller that adjusts the performance of the plant, and a summer that receives an input signal, a feedback signal from the output of the plant, and outputs an error signal to the controller. The error signal is typically generated by subtracting the feedback signal from the input signal and is optionally amplified by a gain factor. The resulting magnitude and polarity of the error signal then determines how the controller should adjust the plant. This type of feedback is also known as negative feedback.
A conventional way of implementing a negative feedback system is via a pure analog approach. For instance, the negative feedback system includes an analog amplifier and an electric motor. The analog amplifier has a positive input terminal that receives an analog input command signal, a negative input terminal that receives a feedback signal from an output of the electric motor, and an output at which a corresponding analog error voltage is generated. The error voltage can be used to directly control a performance parameter of the electric motor, such as the motor's speed or torque. While the analog feedback control system offers minimal delay, it is vulnerable to electrical noise and is difficult to adjust.
It is within this context that the embodiments described herein arise.